CA1159849A - Method for the preparation of a pure alkali metal benzoate besides benzyl alcohol - Google Patents
Method for the preparation of a pure alkali metal benzoate besides benzyl alcoholInfo
- Publication number
- CA1159849A CA1159849A CA000351970A CA351970A CA1159849A CA 1159849 A CA1159849 A CA 1159849A CA 000351970 A CA000351970 A CA 000351970A CA 351970 A CA351970 A CA 351970A CA 1159849 A CA1159849 A CA 1159849A
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- Prior art keywords
- benzoate
- benzyl
- alkali metal
- sodium
- benzyl benzoate
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
- C07C29/09—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by hydrolysis
- C07C29/095—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by hydrolysis of esters of organic acids
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/41—Preparation of salts of carboxylic acids
- C07C51/412—Preparation of salts of carboxylic acids by conversion of the acids, their salts, esters or anhydrides with the same carboxylic acid part
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- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
ABSTRACT
The invention relates to a method for the preparation of a pure alkali metal benzoate, specifically of a pure alkali metal benzoate from benzyl benzoate prepared by oxidation of an alkyl benzene compound, specifically toluene, with a gas containing molecular oxygen, besides benzyl alcohol, Very specifically the invention relates to a method for the preparation of sodium benzoate besides benzyl alcohol.
For this purpose crude benzyl benzoate is subjected to a treatment with a reducing substance to convert impurities, under such circum-stance that, in the process, there will be no conversion of any substantial quantity of benzyl benzoate. Subsequently the benzyl benzoate is saponified to the alkali metal benzoate and benzyl alcohol.
The invention relates to a method for the preparation of a pure alkali metal benzoate, specifically of a pure alkali metal benzoate from benzyl benzoate prepared by oxidation of an alkyl benzene compound, specifically toluene, with a gas containing molecular oxygen, besides benzyl alcohol, Very specifically the invention relates to a method for the preparation of sodium benzoate besides benzyl alcohol.
For this purpose crude benzyl benzoate is subjected to a treatment with a reducing substance to convert impurities, under such circum-stance that, in the process, there will be no conversion of any substantial quantity of benzyl benzoate. Subsequently the benzyl benzoate is saponified to the alkali metal benzoate and benzyl alcohol.
Description
:~L15~l34~
The invention relates to a method for the preparation of a purealkali metal benzoate, specifically o:E a pure alkali metal benzoate from benzyl benzoate prepared by oxidation of an alkyl benzene compound, specifically toluene, with a gas containing molecular oxygen, besides benæyl alcohol. Very specifi-cally the invention relates to a method for the preparation of sodium benzoate besides benzyl alcohol.
Sodium benzoate is an important substance, which is applied, e.g., as z preservative in the food industry. Such a use often requires a high degree of purity of the sodium benzoate. ~lowever, crude sodium benzoate, and specifi-cally sodium benzoate prepared from reaction products of the oxidation of toluene with a gas containing molecular oxygen, contains cumbersome impurities which are very hard to remove. Specifically, it is difficult to obtain from crude sodium benzoate a product which meets the pharmacopoeial requirements.
The purpose of the invention is to provide a solution to this pro-blem. According to the invention crude benzyl benzoate prepared by oxidation of an alkyl benzene compound, specifically toluene, with a gas containing mole-cular oxygenJ is subjected to a treatment with a reducing substance to convert impurities, under such circumstance that, in the process, there will be no conversion of any substantial quantity of benzyl benzoate, which treatment is preferably followed by a washing with an aqueous alkaline solution. Preferably the benzyl benzoate is then distilled. Subsequently the benzyl benzoate is saponified, for instance with an alkali metal hydroxide solution, to the alkali metal benzoate and benzyl alcohol. The reducing substance is hydrogen or the reducing substance is a metal with reducing properties from the groups IA, IIA, IIB, IIIA, IVA, VIIB and VIII of the periodic system in the presence of water.
From the resulting solution the benzyl alcohol can be extracted with, e.g., an organic extractant, such as toluene, and the alcohol can subsequently 1~59~
be recovered by distillation. The alkali metal benzoate can, e.g., be recoveredby evaporation of the aqueous solution obtained.
Preferably this solution is cleaned, before this evaporation of residues of toluene, benzyl alcohol, etc., e.g. by steam distillation.
~la~
The alkali metal benzoate obtained, specifically the sodium benzoate, rneets the said pharmacopoeial requirements, which, as far as sodium benzoate is concerned, mean that, after drying to constant weight, it must be capable, in the following tests, of achieving the 5 stated results 1. acidity/alkalinity - 2 g dissolved in water must not require more than 0.05-0.15 ml 0.1 N aqueous NaOH/HCl for neutra-lization (indicator: phenolphthalein).
10 2. KMnO4 number - 1 g sodium benzoate in acid medium must not require more than 0.5 ml 0.1 N K~lnO4.
3. content - percentage by weight of sodium ben-zoate must be at least 99.5 %.
15 4. colour - a solution of 10 g in 100 ml H20 must be of a lighter colour than or of the same colour as a solution in 100 ml 1 N aqueous sulphuric acid of 4 ml colour standard as described in Nederlandse Farmacopee VI.
5. turbidity - a solution of 10 g in 100 ml H20 must be clearer than a suspension in 100 ml H20 of 1 ml standard suspen-sion of Bolus Alba as described in Nederlandse Farmacopee VI.
6. H2S04 test - the colour of 0.5 g sodium benzoate mixed with 5 ml concentrated H2S04 must, after 15 minutes, not be more intense than the standard solution 'Matching Fluid Q' (MFQ) as described in US Pharmacopeia XIX.
Suitable reducing substances that can be used in applying the method according to the invention are hydrogen, which is preferably used in the presence of a suitablé hydrogenation catalyst, and the metals with reducing properties from the groups IA, IIA, IIB, IIIA, IVA, VIIB and VIII of the periodic system, e.g. magnesium, calcium and in particular zinc, iron and aluminium, which are used in the presence of 9~
water, e.g. by bringing them, in the form of an aqueous suspension, into contact with the benzyl benzoate.
Suitable hydrogenation catalysts in the treatment of the - benzyl benzoate with hydrogen are the known hydrogenation catalysts, e.g. those based on metals from group VIII of the periodic system, e.g. palladium, nickel, platinum, iridium or rhodium. The catalytic material may occur on a carrier, e.g. carbon, aluminium oxide, silica or titanium oxide. Particularly suitable as a catalyst in this method are Raney nickel and palladium-on-carbon. The catalysts are preferably used in quantities of 1-100 mg atom of active substance per kg benzyl benzoate, specifically in quantities of 2-50 mg atom of active substance per kg benzyl benzoate. In applying the method according to the invention generally 2-15 N litres hydrogen is taken up per kg benzyl benzoate and per hour. Often, 5-10 N litres hydrogen per kg benzyl benzoate is taken up per hour. The benzyl benzoate can be brought into contact with hydrogen in different ways. For example, the benzyl benzoate can be stirred in a hydrogen atmosphere for a certain length of time, or the hydrogen can be bubbled through the benzyl benzoate or be passed over it. The duration of the treatment of the benzyl benzoate with hydrogen is mostly between 0.25 and 5 hours, pre-ferably between 0.5 and 1.5 hours. The use of larger quantities of catalyst, of a large excess of hydrogen, and/or the extension of the duration of the treatment are not exluded, but offer no advantages.
This treatment of crude benzyl benzoate with hydrogen is preferably effected at a mild temperature in order to repress hydrogenation of the benzyl benzoate. A 'mild temperature', therefore, is here under-stood to mean a temperature at which the impurities are, but the benzyl benzoate is not substantially hydrogenated. A suitable temperature range is from 290 to 380 K. Particularly suitable are temperatures of between 320 and 360 K. The reaction pressure must be such that the liquid phase is maintained. A suitable reaction pressure is, e.g., between 100 and 1000 kPa, specifically between 200 and 500 kPa.
In the treatment of the benzyl benzoate with the above metals with reducing properties, these metals are mostly consumed in quantities of between 5 and 30 mg atom per kg benzyl benzoate, often in quantities of between lO and 20 mg atom per kg benzyl benzoate.
A suitable temperature range for this treatment of benzyl benzoate is 8~
from the freezing point of the water under the reaction circumstances (about 270 K) to 380 K, specifically from 275 to 360 K. Temperatures higher than 380 K can be applied, if desired. The duration of the treatment is mostly between 0.1 and 5 hours, preferably between 0.5 and 3 hours. Suitable quantities of water during this treatment are, e.g., 1-1000 g per kg benzyl benzoate. Particularly suitable are quan-tities of 20-500 g per kg benzyl benzoate. The reaction pressure must be such that the liquid phase is maintained. A suitable reaction pressure is, e.g., between 50 and 300 kPa, specifi_ally between 75 and 200 kPa.
In order to shorten the time required for the treatment and/or to lower the temperature required for the treatment, a base can be incorporated in the water. If in this process a sufficiently strong alkaline solution, e.g. 2-6 N, is used, washing with an aqueous alkaline solution, after the 'metal-base' treatment, is virtually superfluous. Suitable bases are bases soluble in water, e.g.
hydroxides of alkali metals and earth alkaline metals, the alkali metal carbonates, the alkali metal hydrogen carbonates, ammonia or organic bases soluble in water, e.g. amines. Particularly suitable are the hydroxides and carbonates of sodium and potassium, and calcium hydrox-ide. Suitable are quantities of base to 2500 mmol per kg henzyl benzoate, specifically to 1500 mmol per kg benzyl benzoate. The quantity of base is calculated as the equivalent quantity of NaOH.
Suitable aqueous alkaline solutions for the washing of the treated benzyl benzoate are, e.g., aqueous solutions of hydroxides of alkali metals and earth alkaline metals, alkali metal carbonates, alkali metal hydrogen carbonates, ammonia or organic bases such as amines.
Particularly suitable are aqueous solutions of hydroxides or carbonates of sodium or potassium, and calcium hydroxide. In these washings quan-tities of solution of 0.1-0.5 litre per kg benzyl benzoate of a strength of 2-6 N are often used. The washing is often done at a tem-perature between the freezing point of the water under the prevailing conditions (about 270 K) and 330 K and at a pressure of 50-200 kPa.
Instead of washing with an aqueous alkaline solution, the treated benzyl benzoate can be passed, if desired, over a basic ion exchanger, with which virtually the same results are achieved.
The distillation of the treated benzyl benzoate can be carried out under atmospheric or elevated, specifically, however, at reduced pressure, e.g. at a pressure of 0.5-5 kPa.
The saponification of the benzyl benzoate is carried out with the relative alkali metal hydroxide and/or suitable salts, e.g.
sodium carbonate, potassium carbonate. Particularly suitable are aqueous solutions of preferably 2-4 N. The saponification is often carried out at a temperature of between 350 and 400 K and a pressure of 100-200 kPa.
According to a suitable mode of applying the method accor-ding to the invention, a mixture of the impure benzyl benzoate andwater, optionally containing a base, is passed over a bed of solid metal particles. Particularly suitable for this purpose is a bed of zinc dust. No metal particles need then be separated, after the treatment, from the reaction mixture. Advantages of this procedure are the long on-stream time of the equipment now possible owing to the very slow exhaustion of the material present.
The invention is further elucidated by means of the following non-restrictive examples and of the comparative experiment.
Example I
75 g crude benzyl benzoate, which had been prepared by oxidation of toluene with a gas containing molecular oxygen and 0.375g palladium-on-carbon (5 % by weight of Pd), was heated in a reaction vessel of 500 ml at 323 K for 1.5 hours in the presence of hydrogen while being well shaken. The initial pressure was 445 kPa. After the treatment the pressure had fallen to 245 kPa. After the catalyst had been filtered off, the product was distilled. The main fraction was subsequently washed with cold 3 N aqueous NaOH. After removal of this alkaline water layer the remaining benzyl benzoate was saponified with aqueous NaOH to sodium benzoate and benzyl alcohol. From the resulting solution benzyl alcohol was extracted with toluene. The sodium benzoate was recovered by evaporation of the aqueous solution. Before the eva-poration this solution was cleaned of residues of toluene, benzyl al-cohol, etc., by steam distillation. The sodium benzoate obtained was found, in the above tests; to meet the stated requirements.
Example II
150 g crude benzyl benzoate, prepared by oxidation of toluene with a gas containing molecular oxygen, and 75 ml water and 5 g 98~9 zinc granules were heated for 1 hour at 353-358 K at atmospheric pressure, while being stirred. After this treatment the reaction mixture was cooled down and the zinc granules were separated out.
After that the water layer was separated out. Subsequantly the benzyl benzoate was washed with 75 ml 3 N aqueous NaOH at a temperature of 278-283 K. After removal of this alkaline water layer the remaining benzyl benzoate was distilled. The main fraction was subsequently saponified with aqueous NaOH to sodium benzoate and benzyl alcohol.
From the resulting solution benzyl alcohol was extracted by means of toluene. The sodium benzoate was recovered from the aqueous solution in the same way as in example I. The sodium benzoate obtained was found, in the above tests, to meet the stated requirements.
Example III
120 g crude benzyl benzoate, prepared by oxidation of toluene with a gas containing molecular oxygen, and 12 ml 6 N aqueous NaOH
and 4 g zinc granules, were heated at 313 K for 2.5 hours at atmos-pheric pressure, while being well stirred. After the alkaline water layer and the zinc had been separated out, the benzyl benzoate was distilled. The main fraction was subsequently saponified with aqueous NaOH to sodium benzoate and benzyl alcohol. From the resulting solution benzyl alcohol was extracted with toluene. The sodium benzoate was recovered from the aqueous solution in the same way as in example I.
The sodium benzoate obtained was found, in the above tests, to meet the stated requirements.
Exam~lle IV
200 g crude benzyl benzoate, prepared by oxidation of toluene with a gas containing molecular oxygen, and 1.37 g aluminium powder, were cooled at 278-283 K. With good stirring, 90 ml 3 N aqueous NaOH
was added in drops. The temperature was maintained at 278-283 K. The experiment was done at atmospheric pressure. After 0.5 hour the aluminium and the aqueous alkaline layer were separated out. After that the benzyl benzoate was distilled. The main fraction was sub-sequently saponified with aqueous NaOH to sodium benzoate and benzyl alcohol. From the resulting solution benzyl alcohol was extracted with toluene. The sodium benzoate was recovered from the aqueous solu-tion in the same way as in example I. The sodium benzoate obtained was found, in the above tests, to meet the stated requirements.
Compara_ive experiment 106 g crude benzyl benzoate which had been prepared by oxidation of toluene with a gas containing molecular oxy~en was saponified with aqueous NaOH to s.odium benzoate and benzyl alcohol.
From the resulting solution benzyl alcohol was extracted by means of toluene. The sodium benzoate was recovered from the aqueous solution in the same was as in example I. The sodium benzoate obtained was found, in the above tests, to be capable of meeting the stated requirements only in the acidity/alkalinity test.
The invention relates to a method for the preparation of a purealkali metal benzoate, specifically o:E a pure alkali metal benzoate from benzyl benzoate prepared by oxidation of an alkyl benzene compound, specifically toluene, with a gas containing molecular oxygen, besides benæyl alcohol. Very specifi-cally the invention relates to a method for the preparation of sodium benzoate besides benzyl alcohol.
Sodium benzoate is an important substance, which is applied, e.g., as z preservative in the food industry. Such a use often requires a high degree of purity of the sodium benzoate. ~lowever, crude sodium benzoate, and specifi-cally sodium benzoate prepared from reaction products of the oxidation of toluene with a gas containing molecular oxygen, contains cumbersome impurities which are very hard to remove. Specifically, it is difficult to obtain from crude sodium benzoate a product which meets the pharmacopoeial requirements.
The purpose of the invention is to provide a solution to this pro-blem. According to the invention crude benzyl benzoate prepared by oxidation of an alkyl benzene compound, specifically toluene, with a gas containing mole-cular oxygenJ is subjected to a treatment with a reducing substance to convert impurities, under such circumstance that, in the process, there will be no conversion of any substantial quantity of benzyl benzoate, which treatment is preferably followed by a washing with an aqueous alkaline solution. Preferably the benzyl benzoate is then distilled. Subsequently the benzyl benzoate is saponified, for instance with an alkali metal hydroxide solution, to the alkali metal benzoate and benzyl alcohol. The reducing substance is hydrogen or the reducing substance is a metal with reducing properties from the groups IA, IIA, IIB, IIIA, IVA, VIIB and VIII of the periodic system in the presence of water.
From the resulting solution the benzyl alcohol can be extracted with, e.g., an organic extractant, such as toluene, and the alcohol can subsequently 1~59~
be recovered by distillation. The alkali metal benzoate can, e.g., be recoveredby evaporation of the aqueous solution obtained.
Preferably this solution is cleaned, before this evaporation of residues of toluene, benzyl alcohol, etc., e.g. by steam distillation.
~la~
The alkali metal benzoate obtained, specifically the sodium benzoate, rneets the said pharmacopoeial requirements, which, as far as sodium benzoate is concerned, mean that, after drying to constant weight, it must be capable, in the following tests, of achieving the 5 stated results 1. acidity/alkalinity - 2 g dissolved in water must not require more than 0.05-0.15 ml 0.1 N aqueous NaOH/HCl for neutra-lization (indicator: phenolphthalein).
10 2. KMnO4 number - 1 g sodium benzoate in acid medium must not require more than 0.5 ml 0.1 N K~lnO4.
3. content - percentage by weight of sodium ben-zoate must be at least 99.5 %.
15 4. colour - a solution of 10 g in 100 ml H20 must be of a lighter colour than or of the same colour as a solution in 100 ml 1 N aqueous sulphuric acid of 4 ml colour standard as described in Nederlandse Farmacopee VI.
5. turbidity - a solution of 10 g in 100 ml H20 must be clearer than a suspension in 100 ml H20 of 1 ml standard suspen-sion of Bolus Alba as described in Nederlandse Farmacopee VI.
6. H2S04 test - the colour of 0.5 g sodium benzoate mixed with 5 ml concentrated H2S04 must, after 15 minutes, not be more intense than the standard solution 'Matching Fluid Q' (MFQ) as described in US Pharmacopeia XIX.
Suitable reducing substances that can be used in applying the method according to the invention are hydrogen, which is preferably used in the presence of a suitablé hydrogenation catalyst, and the metals with reducing properties from the groups IA, IIA, IIB, IIIA, IVA, VIIB and VIII of the periodic system, e.g. magnesium, calcium and in particular zinc, iron and aluminium, which are used in the presence of 9~
water, e.g. by bringing them, in the form of an aqueous suspension, into contact with the benzyl benzoate.
Suitable hydrogenation catalysts in the treatment of the - benzyl benzoate with hydrogen are the known hydrogenation catalysts, e.g. those based on metals from group VIII of the periodic system, e.g. palladium, nickel, platinum, iridium or rhodium. The catalytic material may occur on a carrier, e.g. carbon, aluminium oxide, silica or titanium oxide. Particularly suitable as a catalyst in this method are Raney nickel and palladium-on-carbon. The catalysts are preferably used in quantities of 1-100 mg atom of active substance per kg benzyl benzoate, specifically in quantities of 2-50 mg atom of active substance per kg benzyl benzoate. In applying the method according to the invention generally 2-15 N litres hydrogen is taken up per kg benzyl benzoate and per hour. Often, 5-10 N litres hydrogen per kg benzyl benzoate is taken up per hour. The benzyl benzoate can be brought into contact with hydrogen in different ways. For example, the benzyl benzoate can be stirred in a hydrogen atmosphere for a certain length of time, or the hydrogen can be bubbled through the benzyl benzoate or be passed over it. The duration of the treatment of the benzyl benzoate with hydrogen is mostly between 0.25 and 5 hours, pre-ferably between 0.5 and 1.5 hours. The use of larger quantities of catalyst, of a large excess of hydrogen, and/or the extension of the duration of the treatment are not exluded, but offer no advantages.
This treatment of crude benzyl benzoate with hydrogen is preferably effected at a mild temperature in order to repress hydrogenation of the benzyl benzoate. A 'mild temperature', therefore, is here under-stood to mean a temperature at which the impurities are, but the benzyl benzoate is not substantially hydrogenated. A suitable temperature range is from 290 to 380 K. Particularly suitable are temperatures of between 320 and 360 K. The reaction pressure must be such that the liquid phase is maintained. A suitable reaction pressure is, e.g., between 100 and 1000 kPa, specifically between 200 and 500 kPa.
In the treatment of the benzyl benzoate with the above metals with reducing properties, these metals are mostly consumed in quantities of between 5 and 30 mg atom per kg benzyl benzoate, often in quantities of between lO and 20 mg atom per kg benzyl benzoate.
A suitable temperature range for this treatment of benzyl benzoate is 8~
from the freezing point of the water under the reaction circumstances (about 270 K) to 380 K, specifically from 275 to 360 K. Temperatures higher than 380 K can be applied, if desired. The duration of the treatment is mostly between 0.1 and 5 hours, preferably between 0.5 and 3 hours. Suitable quantities of water during this treatment are, e.g., 1-1000 g per kg benzyl benzoate. Particularly suitable are quan-tities of 20-500 g per kg benzyl benzoate. The reaction pressure must be such that the liquid phase is maintained. A suitable reaction pressure is, e.g., between 50 and 300 kPa, specifi_ally between 75 and 200 kPa.
In order to shorten the time required for the treatment and/or to lower the temperature required for the treatment, a base can be incorporated in the water. If in this process a sufficiently strong alkaline solution, e.g. 2-6 N, is used, washing with an aqueous alkaline solution, after the 'metal-base' treatment, is virtually superfluous. Suitable bases are bases soluble in water, e.g.
hydroxides of alkali metals and earth alkaline metals, the alkali metal carbonates, the alkali metal hydrogen carbonates, ammonia or organic bases soluble in water, e.g. amines. Particularly suitable are the hydroxides and carbonates of sodium and potassium, and calcium hydrox-ide. Suitable are quantities of base to 2500 mmol per kg henzyl benzoate, specifically to 1500 mmol per kg benzyl benzoate. The quantity of base is calculated as the equivalent quantity of NaOH.
Suitable aqueous alkaline solutions for the washing of the treated benzyl benzoate are, e.g., aqueous solutions of hydroxides of alkali metals and earth alkaline metals, alkali metal carbonates, alkali metal hydrogen carbonates, ammonia or organic bases such as amines.
Particularly suitable are aqueous solutions of hydroxides or carbonates of sodium or potassium, and calcium hydroxide. In these washings quan-tities of solution of 0.1-0.5 litre per kg benzyl benzoate of a strength of 2-6 N are often used. The washing is often done at a tem-perature between the freezing point of the water under the prevailing conditions (about 270 K) and 330 K and at a pressure of 50-200 kPa.
Instead of washing with an aqueous alkaline solution, the treated benzyl benzoate can be passed, if desired, over a basic ion exchanger, with which virtually the same results are achieved.
The distillation of the treated benzyl benzoate can be carried out under atmospheric or elevated, specifically, however, at reduced pressure, e.g. at a pressure of 0.5-5 kPa.
The saponification of the benzyl benzoate is carried out with the relative alkali metal hydroxide and/or suitable salts, e.g.
sodium carbonate, potassium carbonate. Particularly suitable are aqueous solutions of preferably 2-4 N. The saponification is often carried out at a temperature of between 350 and 400 K and a pressure of 100-200 kPa.
According to a suitable mode of applying the method accor-ding to the invention, a mixture of the impure benzyl benzoate andwater, optionally containing a base, is passed over a bed of solid metal particles. Particularly suitable for this purpose is a bed of zinc dust. No metal particles need then be separated, after the treatment, from the reaction mixture. Advantages of this procedure are the long on-stream time of the equipment now possible owing to the very slow exhaustion of the material present.
The invention is further elucidated by means of the following non-restrictive examples and of the comparative experiment.
Example I
75 g crude benzyl benzoate, which had been prepared by oxidation of toluene with a gas containing molecular oxygen and 0.375g palladium-on-carbon (5 % by weight of Pd), was heated in a reaction vessel of 500 ml at 323 K for 1.5 hours in the presence of hydrogen while being well shaken. The initial pressure was 445 kPa. After the treatment the pressure had fallen to 245 kPa. After the catalyst had been filtered off, the product was distilled. The main fraction was subsequently washed with cold 3 N aqueous NaOH. After removal of this alkaline water layer the remaining benzyl benzoate was saponified with aqueous NaOH to sodium benzoate and benzyl alcohol. From the resulting solution benzyl alcohol was extracted with toluene. The sodium benzoate was recovered by evaporation of the aqueous solution. Before the eva-poration this solution was cleaned of residues of toluene, benzyl al-cohol, etc., by steam distillation. The sodium benzoate obtained was found, in the above tests; to meet the stated requirements.
Example II
150 g crude benzyl benzoate, prepared by oxidation of toluene with a gas containing molecular oxygen, and 75 ml water and 5 g 98~9 zinc granules were heated for 1 hour at 353-358 K at atmospheric pressure, while being stirred. After this treatment the reaction mixture was cooled down and the zinc granules were separated out.
After that the water layer was separated out. Subsequantly the benzyl benzoate was washed with 75 ml 3 N aqueous NaOH at a temperature of 278-283 K. After removal of this alkaline water layer the remaining benzyl benzoate was distilled. The main fraction was subsequently saponified with aqueous NaOH to sodium benzoate and benzyl alcohol.
From the resulting solution benzyl alcohol was extracted by means of toluene. The sodium benzoate was recovered from the aqueous solution in the same way as in example I. The sodium benzoate obtained was found, in the above tests, to meet the stated requirements.
Example III
120 g crude benzyl benzoate, prepared by oxidation of toluene with a gas containing molecular oxygen, and 12 ml 6 N aqueous NaOH
and 4 g zinc granules, were heated at 313 K for 2.5 hours at atmos-pheric pressure, while being well stirred. After the alkaline water layer and the zinc had been separated out, the benzyl benzoate was distilled. The main fraction was subsequently saponified with aqueous NaOH to sodium benzoate and benzyl alcohol. From the resulting solution benzyl alcohol was extracted with toluene. The sodium benzoate was recovered from the aqueous solution in the same way as in example I.
The sodium benzoate obtained was found, in the above tests, to meet the stated requirements.
Exam~lle IV
200 g crude benzyl benzoate, prepared by oxidation of toluene with a gas containing molecular oxygen, and 1.37 g aluminium powder, were cooled at 278-283 K. With good stirring, 90 ml 3 N aqueous NaOH
was added in drops. The temperature was maintained at 278-283 K. The experiment was done at atmospheric pressure. After 0.5 hour the aluminium and the aqueous alkaline layer were separated out. After that the benzyl benzoate was distilled. The main fraction was sub-sequently saponified with aqueous NaOH to sodium benzoate and benzyl alcohol. From the resulting solution benzyl alcohol was extracted with toluene. The sodium benzoate was recovered from the aqueous solu-tion in the same way as in example I. The sodium benzoate obtained was found, in the above tests, to meet the stated requirements.
Compara_ive experiment 106 g crude benzyl benzoate which had been prepared by oxidation of toluene with a gas containing molecular oxy~en was saponified with aqueous NaOH to s.odium benzoate and benzyl alcohol.
From the resulting solution benzyl alcohol was extracted by means of toluene. The sodium benzoate was recovered from the aqueous solution in the same was as in example I. The sodium benzoate obtained was found, in the above tests, to be capable of meeting the stated requirements only in the acidity/alkalinity test.
Claims (26)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. Method for the preparation of pure alkali metal benzoate besides benzyl alcohol, characterized in that crude benzyl benzoate is prepared by oxidation of an alkylbenzene compound with a gas containing molecular oxygen and is then subjected to a treatment with a reducing substance to convert impurities, under such circumstances that, in the process, there will be no conversion of any substantial quantity of benzyl benzoate, wherein the reducing substance is hydrogen or the reducing substance is a metal with reducing pro-perties from the groups IA, IIA, IIB, IIIA, IVA, VIIB and VIII of the periodic system in the presence of water, and is subsequently saponified to alkali metal benzoate.
2. Method according to claim 1, characterized in that the alkylbenzene compound is toluene.
3. Method according to claim 1 characterized in that the alkali metal benzoate is sodium benzoate.
4. Method according to claim 1, characterized in that the reducing substance is hydrogen and the treatment is carried out in the presence of a suitable hydrogenation catalyst.
5. Method according to claim 4, characterized in that the catalyst comprises a metal from group VIII of the periodic system.
6. Method according to claim 4, characterized in that, Raney nickel is the hydrogenation catalyst.
7. Method according to claim 4, characterized in that, palladium-on-carbon is the hydrogenation catalyst.
8. Method according to claim 1, 2 or 3, characterized in that the metal with reducing properties is zinc.
9. Method according to claim 1, 2 or 3, characterized in that the metal with reducing properties is iron.
10. Method according to claim 1, 2 or 3, characterized in that the metal with reducing properties is aluminium.
11. Method according to claim 1, 2 or 3, characterized in that the metal with reducing properties is applied as an aqueous suspension.
12. Method according to claim 1, characterized in that a base is incor-porated in the water.
13. Method according to claim 12, characterized in that, as base, a hydroxide of sodium, potassium or calcium is used.
14. Method according to claim 12, characterized in that, as base, a carbonate of sodium or potassium is used.
15. Method according to claim 1, characterized in that a mixture of the crude benzyl benzoate and water is passed over a bed of solid particles of the metal.
16. Method according to claim 15, characterized in that a bed of zinc dust is used.
17. Method according to claim 1, characterized in that the treated benzyl benzoate is washed with an aqueous alkaline solution.
18. Method according to claim 17, characterized in that the aqueous alkaline solution comprises a hydroxide of sodium, potassium and/or calcium is used.
19. Method according to claim 17, characterized in that the aqueous alkaline solution comprises a carbonate of sodium and/or potassium is used.
20. Method according to claim 1, 2 or 3, characterized in that the treated benzyl benzoate is distilled.
21. Method according to claim 1, 2 or 3, characterized in that the treated benzyl benzoate is saponified to sodium benzoate besides benzyl alcohol.
22. Method according to claim 1, characterized in that, besides a pure alkali metal benzoate, the benzyl alcohol is also recovered.
23. Method according to claim 22, characterized in that the benzyl alcohol is distilled from an extract wherein the extract is formed by subjecting the reaction mixture which is formed after the saponification of the treated benzyl benzoate, to an extraction with an organic extractant.
24. Method according to claim 23, characterized in that, as organic extractant, toluene is used.
25. Method according to claim 1, characterized in that the alkali metal benzoate is cleaned of organic residues.
26. Method according to claim 25, characterized in that the cleaning comprises steam distillation.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NL7903876A NL7903876A (en) | 1979-05-17 | 1979-05-17 | PROCESS FOR PREPARING A PURE ALKALINE METAL BENZATE NEXT TO BENZYL ALCOHOL. |
| NL7903876 | 1979-05-17 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1159849A true CA1159849A (en) | 1984-01-03 |
Family
ID=19833200
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000351970A Expired CA1159849A (en) | 1979-05-17 | 1980-05-14 | Method for the preparation of a pure alkali metal benzoate besides benzyl alcohol |
Country Status (9)
| Country | Link |
|---|---|
| US (1) | US4296245A (en) |
| EP (1) | EP0019341B1 (en) |
| JP (1) | JPS55153731A (en) |
| CA (1) | CA1159849A (en) |
| DE (1) | DE3063442D1 (en) |
| ES (1) | ES491479A0 (en) |
| IN (1) | IN151649B (en) |
| NL (1) | NL7903876A (en) |
| YU (1) | YU122980A (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3144316A1 (en) * | 1981-11-07 | 1983-05-19 | Bayer Ag, 5090 Leverkusen | METHOD FOR PRODUCING BENZOYL CHLORIDE |
| NL1007829C2 (en) * | 1997-12-18 | 1999-06-21 | Dsm Nv | Process for the preparation of benzyl alcohol. |
| US6669848B2 (en) * | 2002-01-31 | 2003-12-30 | Tillin, Inc. | Methods of treating commercial grade preservatives to remove undesirable odors and flavors |
| CN115160132B (en) * | 2022-08-06 | 2023-10-31 | 天津大加化工有限公司 | Production process of benzyl benzoate |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1003709B (en) * | 1954-07-21 | 1957-03-07 | Basf Ag | Process for the lossless purification of crude esters of higher molecular weight fatty acids by distillation |
| US3642883A (en) * | 1968-12-16 | 1972-02-15 | Standard Oil Co | Process for removal of aromatic bromine in benzoic acid production |
| UST880007I4 (en) | 1970-01-15 | 1970-11-24 | Defensive publication | |
| DE2007783A1 (en) * | 1970-02-20 | 1971-09-02 | ||
| DE2636489C2 (en) * | 1976-08-13 | 1984-01-12 | Bayer Ag, 5090 Leverkusen | Process for the production of sodium benzoate |
| IT1086499B (en) * | 1976-09-24 | 1985-05-28 | Teijin Hercules Chem Co Ltd | PROCEDURE FOR PREPARING AROMATIC CARBOXYLIC ACIDS OR THEIR METHYL ESTERS WITH INCREASED YIELDS |
| NL7805415A (en) * | 1978-05-19 | 1979-11-21 | Stamicarbon | PROCESS FOR PREPARING AN ALKALINE METAL BENZOATE IN ADDITION TO A BENZYL ALKOHOL. |
-
1979
- 1979-05-17 NL NL7903876A patent/NL7903876A/en not_active Application Discontinuation
-
1980
- 1980-05-09 YU YU01229/80A patent/YU122980A/en unknown
- 1980-05-13 DE DE8080200444T patent/DE3063442D1/en not_active Expired
- 1980-05-13 EP EP80200444A patent/EP0019341B1/en not_active Expired
- 1980-05-14 CA CA000351970A patent/CA1159849A/en not_active Expired
- 1980-05-14 ES ES491479A patent/ES491479A0/en active Granted
- 1980-05-16 JP JP6517980A patent/JPS55153731A/en active Pending
- 1980-05-16 US US06/150,690 patent/US4296245A/en not_active Expired - Lifetime
- 1980-05-27 IN IN619/CAL/80A patent/IN151649B/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| ES8102083A1 (en) | 1980-12-16 |
| YU122980A (en) | 1983-09-30 |
| IN151649B (en) | 1983-06-18 |
| DE3063442D1 (en) | 1983-07-07 |
| EP0019341A1 (en) | 1980-11-26 |
| US4296245A (en) | 1981-10-20 |
| ES491479A0 (en) | 1980-12-16 |
| JPS55153731A (en) | 1980-11-29 |
| NL7903876A (en) | 1980-11-19 |
| EP0019341B1 (en) | 1983-05-25 |
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